

from sortedcontainers import SortedDict


arr=[1,2,3]
print(arr[4:])


# Python 3.7+ 普通字典已经有序
regular_dict = SortedDict()
regular_dict['a'] = 1
regular_dict['c'] = 3
regular_dict['b'] = 2

# 遍历时会按照插入顺序
for key, value in regular_dict.items():
    print(key, value)